Recent careful measurements of oculomotor function in normal individuals reveal that oculomotor compensation for head, eye and body movements is not perfect, permitting retinal image motion at velocities averaging 0.5-2 degrees/sec. The interesting question is why this amount of motion blur does not impair pattern recognition. Vernier acuity is a very sensitive measure of the human ability to judge relative spatial location. The average observer can detect that two lines are misaligned when the magnitude of the spatial offset is only 10 arc seconds. Yet vernier acuity measured for durations too brief to allow the eyes to pursue the target is unaffected by motion at velocities ranging up to 2 degrees/sec. Psychophsical measurements will be used to explore how the visual system can compensate so well for motion blur, preserving precise information about spatial configuration. Specifically, the proposed research will examine three questions: 1) What is the characteristic pattern of neural activity, as measured by its effects on local thresholds, produced by a moving contour? 2) Can a stationary contour, blurred to simulate the effects of motion blur, be localized with the same accuracy as a sharp contour? 3) Does the visual system use the information from the temporal response pattern created by the moving contour to determine relative spatial position? In addition to supplying fundamental information about spatial-temporal processsing in the human visual system, this research should provide information useful in understanding the sensory world of individuals suffering from chronic oculomotor instability.